Function ordermap::find_existing_entry_at

pub(crate) fn find_existing_entry_at<Sz>(
    indices: &[Pos],
    hash: HashValue,
    mask: usize,
    entry_index: usize,
) -> usize
where
    Sz: Size,

Find, in the indices, an entry that already exists at a known position inside self.entries in the OrderMap.

This is effectively reverse lookup, from the entries into the hash buckets.

Return the probe index (into self.indices)

• indices: The self.indices of the map,
• hash: The full hash value from the bucket
• mask: self.mask.
• entry_index: The index of the entry in self.entries